The protection of crops from weeds and other vegetation which inhibit crop growth is a constantly recurring problem in agriculture. To help combat this problem, researchers in the field of synthetic chemistry have produced an extensive variety of chemicals and chemical formulations effective in the control of such unwanted growth. Secondary metabolites produced by microbes have in some instances been used for weed and pest control in agricultural applications.
Plants are capable of activating a large array of defense mechanisms in response to pathogen attack, some of which are preexisting and others are inducible. In the past few years it has become apparent that jasmonic acid (JA) and salicylic acid (SA) signaling can play an important role in regulation of pathogen defenses. SA signaling and JA signaling pathways are interconnected in complicated ways. For example, some studies have shown that SA signaling and JA signaling are mutually inhibitory (Creelman et al., Annu. Rev. Plant Physiol. Plant Mol. Biol., 48:355 (1997); Gupta et al., Molec Plant-Microbe Interact 13(5): 503-511 (2000).
Pathogen infections and weeds can cause significant crop losses worldwide. Pathogens can also lead to disturbances in natural ecosystems. An understanding how plants control infections and respond to herbicides, for example via expression of defense mechanisms, can lead to new and beneficial ways to handle plant pathogens and control weed problems.